The neural substrate of spectral preference in Drosophila.
Drosophila vision is mediated by inputs from three types of photoreceptor neurons; R1-R6 mediate achromatic motion detection, while R7 and R8 constitute two chromatic channels. Neural circuits for processing chromatic information are not known. Here, we identified the first-order interneurons downstream of the chromatic channels. Serial EM revealed that small-field projection neurons Tm5 and Tm9 receive direct synaptic input from R7 and R8, respectively, and indirect input from R1-R6, qualifying them to function as color-opponent neurons. Wide-field Dm8 amacrine neurons receive input from 13-16 UV-sensing R7s and provide output to projection neurons. Using a combinatorial expression system to manipulate activity in different neuron subtypes, we determined that Dm8 neurons are necessary and sufficient for flies to exhibit phototaxis toward ultraviolet instead of green light. We propose that Dm8 sacrifices spatial resolution for sensitivity by relaying signals from multiple R7s to projection neurons, which then provide output to higher visual centers.
Gao
Shuying
S
Unit on Neuronal Connectivity, Laboratory of Gene Regulation and Development, National Institute of Child Health and Human Development, NIH, Bethesda, MD 20892, USA.
Takemura
Shin-Ya
SY
Ting
Chun-Yuan
CY
Huang
Songling
S
Lu
Zhiyuan
Z
Luan
Haojiang
H
Rister
Jens
J
Thum
Andreas S
AS
Yang
Meiluen
M
Hong
Sung-Tae
ST
Wang
Jing W
JW
Odenwald
Ward F
WF
White
Benjamin H
BH
Meinertzhagen
Ian A
IA
Lee
Chi-Hon
CH
D025042:Amacrine Cells / Q000166:cytology / Q000502:physiology / Q000528:radiation effects; D000818:Animals; D055253:Color Vision / Q000502:physiology* / Q000528:radiation effects; D054910:Compound Eye, Arthropod / Q000166:cytology / Q000502:physiology* / Q000528:radiation effects; D004331:Drosophila melanogaster / Q000166:cytology / Q000502:physiology*; D007395:Interneurons / Q000166:cytology / Q000502:physiology* / Q000528:radiation effects; D055537:Light Signal Transduction / Q000502:physiology / Q000528:radiation effects; D009899:Optic Lobe, Nonmammalian / Q000166:cytology / Q000502:physiology; D010775:Photic Stimulation; D017956:Photoreceptor Cells, Invertebrate / Q000166:cytology / Q000502:physiology* / Q000528:radiation effects; D013569:Synapses / Q000502:physiology / Q000528:radiation effects / Q000648:ultrastructure; D009435:Synaptic Transmission / Q000502:physiology / Q000528:radiation effects; D014466:Ultraviolet Rays; D014795:Visual Pathways / Q000166:cytology / Q000502:physiology* / Q000528:radiation effects